Editing 網路服務連線測試

如何測試與排除網路服務連線問題。找出問題發生的地方：(1) 伺服器上的本地服務 (localhost) (2) 從區域網路到伺服器 (3) 從廣域網路到伺服器

=== 如何連線到網路服務 (Web 服務) ===

如果服務是網站伺服器 (web service)：
* (1) 打開瀏覽器，(2) 輸入地址：{{kbd | key = <nowiki>http://127.0.0.1</nowiki> }} 或 {{kbd | key =<nowiki>http://the.domain</nowiki>}}

* Linux Lynx 指令： 
*# (如果尚未安裝lynx，則為可選操作) {{kbd | key = <nowiki>yum install lynx</nowiki>}} 適用於CentOS / {{kbd | key = <nowiki>sudo apt-get install lynx</nowiki>}} 適用於Ubuntu<ref>[http://www.addictivetips.com/ubuntu-linux-tips/install-and-use-lynx-on-ubuntu/ 在Ubuntu上安裝和使用Lynx瀏覽器]</ref>
*# {{kbd | key = <nowiki>lynx http://127.0.0.1</nowiki>}} <ref>[http://lynx.isc.org/lynx2.8.7/lynx2-8-7/lynx_help/Lynx_users_guide.html Lynx使用者指南 v2.8.7]</ref> 適用於{{Linux}}

* telnet 指令
*# {{kbd | key = telnet 127.0.0.1 <PORT>}} 例如 {{kbd | key = telnet 127.0.0.1 80}} 或 {{kbd | key = telnet the.domain 80}}
*# (在telnet連接80埠後，輸入) {{kbd_plus | key1 = get | key2 = SPACE}}<ref>[http://www.simplescripts.de/http-check-port-80-telnet-command.htm 使用Telnet指令檢查HTTP埠口80]</ref>

* curl<ref>[https://curl.se/docs/manpage.html curl - 使用方法]</ref>: {{kbd | key = <nowiki>curl -vL http://IP:Port</nowiki>}}
** (如果尚未安裝curl指令，則為可選操作) [https://help.ubidots.com/en/articles/2165289-learn-how-to-install-run-curl-on-windows-macosx-linux 在Windows/MacOSX/Linux上安裝和運行cURL | Ubidots幫助中心]
** 指令範例：
*** (1) 使用 {{kbd | key = <nowiki>curl -voL https://www.google.com</nowiki>}} 將輸出寫入<file>而非stdout
*** (2) 使用 {{kbd | key = <nowiki>curl -vL https://www.google.com</nowiki>}} 或 {{kbd | key = <nowiki>curl -voL /dev/null https://www.google.com</nowiki>}} 將輸出寫入stdout
*** (3) 使用 {{kbd | key = <nowiki>curl -vOL https://www.google.com/index.html</nowiki>}} 將輸出寫入<file>並使用遠程檔案名
** 如果失敗，將顯示消息："failed: Connection refused"

* Linux [https://www.gnu.org/software/wget/ wget] 軟體例如 {{kbd | key = <nowiki>wget https://www.google.com</nowiki>}}

* 使用第三方網站監控服務：[[Web Ping]] 

如果服務不是網站伺服器，則使用telnet
# (可選) [https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/cc771275(v=ws.10) 在{{Win}}上安裝Telnet用戶端 | Microsoft文件]。[https://medium.com/@blackSource/bring-telnet-back-on-macos-high-sierra-11de98de1544 在macOS high Sierra上重啟telnet – Ayuth Mangmesap (blackSource) – Medium] 在{{Mac}}
# {{kbd | key = telnet 127.0.0.1 <PORT>}} 如果連接網頁服務失敗。它將顯示消息："telnet: 無法連接到遠程主機：連接被拒絕"

如果安裝了Python，則使用替代網站服務

* (對於python 2.x) {{kbd | key=<nowiki>python -m SimpleHTTPServer <port></nowiki>}}<ref>[https://docs.python.org/2/library/simplehttpserver.html 20.19. SimpleHTTPServer — 簡單HTTP請求處理器 — Python 2.7.17 文件]</ref>
* (對於python 3.x) {{kbd | key=<nowiki>python -m http.server <port></nowiki>}}<ref>[https://docs.python.org/3.8/library/http.server.html?highlight=http%20server#module-http.server http.server — HTTP伺服器 — Python 3.8.1 文件]</ref>

== 測試本地網路服務的連接性 ==
WAN &#9675; -------&gt; &#9675; LAN -------&gt; <span style="color:red">&#9679; 伺服器</span>

: [[Image:Owl icon.jpg]] 如果您有管理權限通過SSH或遠程桌面服務登錄伺服器。

=== 檢查您的電腦/伺服器是否被指派了IP位址 ===

* {{Linux}}：(1) 檢查IP位址。{{kbd | key = ifconfig}}。 (2) 重新分配IP位址並重新啟動網路服務。{{kbd | key = service network restart}} 用於CentOS<ref>[http://askubuntu.com/questions/230698/how-to-restart-the-networking-service 如何重新啟動網路服務？ - Ask Ubuntu]</ref>
* {{Win}}：檢查IP位址。{{kbd | key = ifconfig/all}} 
* 更多關於[[網路問題]]

=== 檢查網路服務是否已成功啟動？ ===
* Apache {{kbd | key = /etc/init.d/httpd status}} 在CentOS7上 <ref>[https://www.e2enetworks.com/help/knowledge-base/how-to-check-running-status-of-lamp-stack/ 如何檢查LAMP堆棧的運行狀態 | E2E Networks知識庫]</ref>
* nginx {{kbd | key = sudo service nginx status}} 在CentOS7上 
* Docker容器 {{kbd | key = docker ps}} 檢查容器是否在運行和暴露埠口<ref>[https://docs.docker.com/engine/reference/commandline/ps/ docker ps | Docker文件]</ref>

=== 檢查MySQL是否已成功啟動？ ===
==== 使用lsof指令 ==== 
{{kbd | key = lsof -i:3306}} 在{{Mac}}或{{Linux}} 在Unix類操作系統中用於列出打開的文件及打開它們的進程。

* lsof：這代表"列出打開的文件"。它是一個命令行工具，顯示有關由進程打開的文件的資訊。在Unix和Linux中，一切都被視為文件（包括硬體設備、套接字和目錄），因此lsof是系統管理員監控和排除系統行為問題的強大工具。

* -i：這個選項告訴lsof僅顯示網絡文件。在Unix和Linux中，網絡連接被視為文件。-i選項可用於根據互聯網地址或網絡協議過濾連接。

* :3306：這指定了埠號。埠3306通常被MySQL使用，這是一個流行的數據庫管理系統。通過包括:3306，您要求lsof列出所有與埠3306相關的網絡文件（包括套接字連接）。

輸出範例：localhost:mysql (LISTEN) 意味著MySQL已成功啟動

<pre>
COMMAND     PID      USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
mysqld    93034 account   29u  IPv4 0xxxx      0t0  TCP localhost:mysql (LISTEN)
</pre>

==== 使用ps指令 ====

{{kbd | key = <nowiki>ps aux | grep mysql</nowiki>}} 在{{Mac}}

如果MySQL已成功啟動的輸出範例：
<pre>
_mysql           11083   0.3  0.2 409657280  31424   ??  Ss    2:12下午   0:01.07 /usr/local/mysql/bin/mysqld --user=_mysql --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --log-error=/usr/local/mysql/data/mysqld.local.err --pid-file=/usr/local/mysql/data/mysqld.local.pid --keyring-file-data=/usr/local/mysql/keyring/keyring --early-plugin-load=keyring_file=keyring_file.so
ACCOUNT        12349   0.0  0.0 408645328   1648 s011  S+    2:14下午   0:00.00 grep mysql
</pre>

如果MySQL沒有成功啟動的示例輸出：

<pre>
ACCOUNT        12349   0.0  0.0 408645328   1648 s011  S+    2:14下午   0:00.00 grep mysql
</pre>

=== 檢查埠是否被其他進程佔用？ ===
檢查埠是否被其他協議使用

[https://www.speedguide.net/ports.php SG TCP/IP埠數據庫]
[https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers 維基百科 - TCP和UDP埠號列表]


[[Find process running on port]]

* {{Linux}} 
** [http://linux.die.net/man/1/nmap nmap] "Network exploration tool and security / port scanner." e.g. {{kbd | key = <nowiki>nmap -p 80,443 ip</nowiki>}}
** [http://linux.die.net/man/8/ss ss] "utility to investigate sockets" e.g. {{kbd | key = <nowiki>ss -tnlp | grep 80</nowiki>}} or using OR operator<ref>[http://www.thegeekstuff.com/2011/10/grep-or-and-not-operators/ 7 Linux Grep OR, Grep AND, Grep NOT Operator Examples]</ref> {{kbd | key = <nowiki>ss -tnlp | grep '80\|443'</nowiki>}}
** [http://linuxcommand.org/man_pages/ps1.html ps] List the current processes. Input {{kbd | key = <nowiki>ps -aux | grep "PORT_NUMBER"</nowiki>}} e.g. {{kbd | key = <nowiki>ps -aux | grep 443</nowiki>}}
** [https://docs.oracle.com/cd/E19504-01/802-5753/6i9g71m3i/index.html netstat Command] {{kbd | key=<nowiki>netstat -tulpn | grep LISTEN</nowiki>}} e.g. 
** [https://docs.docker.com/engine/reference/commandline/port/ docker port | Docker Documentation]

Example output of netstat command
<pre>
$ netstat -tulpn | grep LISTEN

tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      - 

// means the 80 port service is running
</pre>

* {{Win}} 
** Using the software [http://www.nirsoft.net/utils/cports.html CurrPorts] to check the process and port. e.g. Apache will not running if the 80 port was occupied by skype<ref>[http://stackoverflow.com/questions/4705005/how-to-solve-wamp-and-skype-conflict-on-windows-7 How to solve WAMP and Skype conflict on Windows 7? - Stack Overflow]</ref>.

=== Check if a port is blocked by browser ===
Check if a port is blocked by browser<ref>[https://blog.miniasp.com/post/2022/05/02/Dont-use-ERR_UNSAFE_PORT-for-your-website?fbclid=IwAR2y9D60H-j8-5T1zJixTU-L2ydbn7LgnWpG1v53fyaKCyuuqx2MqfU80fI 開發與部署網站時需注意不要使用到 ERR_UNSAFE_PORT 不安全的埠號 | The Will Will Web]</ref>
* {{Chrome}} [https://chromium.googlesource.com/chromium/src.git/+/refs/heads/master/net/base/port_util.cc#52 net/base/port_util.cc - chromium/src.git - Git at Google]
* [https://fetch.spec.whatwg.org/#port-blocking Fetch Standard] 2.9. Port blocking


=== Is the port opened for external users? ===
Check the OS firewall or protected by antivirus software

** {{Linux}}
*** [http://linux.die.net/man/8/iptables iptables]: (1) {{kbd | key = iptables -L}} to list all rules<ref>[http://wiki.centos.org/HowTos/Network/IPTables HowTos/Network/IPTables - CentOS Wiki]</ref> (2) rule with smaller line-number will override the rule with larger line-number<ref>[https://fedoraproject.org/wiki/How_to_edit_iptables_rules?rd=User_talk:Rforlot How to edit iptables rules - FedoraProject]</ref>
*** [https://fedoraproject.org/wiki/FirewallD FirewallD] rules: (1) {{kbd | key = <nowiki>sudo firewall-cmd --get-default-zone</nowiki>}} return 'public' (2) {{kbd | key = <nowiki>sudo firewall-cmd --list-all --zone=public</nowiki>}}<ref>[https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-using-firewalld-on-centos-7 How To Set Up a Firewall Using FirewallD on CentOS 7 | DigitalOcean]</ref> (3) Allow port with FirewallD
*** [http://linux.die.net/man/8/semanage SELinux Policy Management]:  (1) After installed {{kbd | key =policycoreutils-python}}<ref>[http://sharadchhetri.com/2014/10/07/semanage-command-found-centos-7-rhel-7/ semanage command not found on CentOS 7 and RHEL 7]</ref>, input {{kbd | key = <nowiki>semanage port -l</nowiki>}} to list open ports. (2) Allow port with semanage.
** {{Win}} [https://technet.microsoft.com/en-us/library/cc754274.aspx?f=255&MSPPError=-2147217396 Windows Firewall with Advanced Security] -> configure firewall rules
** protected by antivirus software?
* connect to localhost ex: {{kbd | key= telnet 127.0.0.1 23}} where 23 is the port number where the service running
** [https://technet.microsoft.com/en-us/library/cc771275(v=ws.10).aspx Install Telnet Client] on {{Win}}
** if the local service is web server, you can also try  {{kbd | key = <nowiki>lynx http://127.0.0.1</nowiki>}} for {{Linux}}
* double [[Testing#check_the_server.2Fservice_logs | check the server/service logs]]

== Test connectivity from LAN to the server ==
WAN &#9675; -------&gt; <span style="color:red">&#9679; LAN -------&gt; &#9679; server</span>

Testing on LAN (local network, subnet scope): The different servers between LAN or with the same ip class (ex: 1.2.3.*) and may not have the firewall limit. [https://en.wikipedia.org/wiki/Private_network Private network] / Private IP address

* Is the service alive? 
* Connect to the internal IP eg: {{kbd | key= telnet 172.18.0.1 23}} (1) IP start with 172.18... is [http://www.itcom.itd.umich.edu/backbone/umnet/privateIP.html Private IP Network Numbers] (2) where 23 is the port number where the service running
* If the local service is web server, you can also try to connect the internal IP e.g. {{kbd | key = <nowiki>lynx http://172.18.0.1</nowiki>}} for {{Linux}}
* Double [[Testing#check_the_server.2Fservice_logs | check the server/service logs]]
* Is the internal IP correct?

== Test connectivity from WAN to the remote server ==
<span style="color:red">WAN &#9679; -------&gt; &#9679; LAN -------&gt; &#9679; server</span>

We met the trouble on WAN (wide area network). If we do no have the administrative permission, the tests we can do as follows:
*  [http://downforeveryoneorjustme.com/ Down for everyone or just me?] more on [[Web_Ping#同時從世界各處測試網站連線 | Web Ping]]
* Switch to different ISP? Is hardware firewall enabled?
* Is gateway alive?
* Is DNS alive?
* Is the external IP correct? 
** If the firewall rule is IP specified, verify the IP if correct from [http://whatismyipaddress.com/ What Is My IP Address?] or web access log.
** Query the [http://ipinfo.io/ IP Address Details - ipinfo.io]. e.g. Input the command {{kbd | key = <nowiki>curl ipinfo.io/ip</nowiki>}}<ref>[https://askubuntu.com/questions/95910/command-for-determining-my-public-ip#comment1318649_95910 networking - Command for determining my public IP? - Ask Ubuntu]</ref> for {{Mac}} & {{Linux}}
* Is the port was opened for external users? [http://www.portchecktool.com/ Open Port Check Tool - Port Forwarding Port Check Tool]
* Is institutional/ISP firewall enabled? Contact your MIS. ([https://en.wikipedia.org/wiki/Management_information_system Management information system]) of your company or ISP?

other issue: 
* bandwidth cost too much by certain users
* exceed the request limit of (hardware) firewall
* the external connection of updated Windows was down until reboot {{Win}}
* Amazon EC2 security group
* refresh browser cache: [http://refreshyourcache.com/en/cache/ Refresh your cache - When hitting F5 just isn't enough!]

== Tools ==

# {{Gd}} [http://www.nirsoft.net/utils/cports.html CurrPorts: Monitoring TCP/IP network connections on Windows]
# [http://portforward.com/help/portcheck.htm PFPortCheck Program]: check TCP/UDP port from localhost(where you installed the program) to portforward.com
# [http://technet.microsoft.com/en-us/sysinternals/bb897437 TCPView for Windows]
# [http://check-host.net/ Check server: Check host - online website monitoring, Check IP] "checks the possibility of a TCP connection to host's specified port from different locations around the world." quoted from website. {{access | date=2015-08-02}}

== Related articles ==
* [https://errerrors.blogspot.com/2022/07/blog-post.html 怎樣排除網路連線逾時 (network connection timed out) 問題]

== References ==
<references />

{{Template:Troubleshooting}}

[[Category:Software]]
[[Category:Programming]]
[[Category:Web_Dev]]
[[Category:MySQL]]
[[Category:Linux]]
[[Category:Testing]]